Secure access systems are used in a wide array of settings spanning industrial, medical, military, retail and financial. In addition to controlling access, the systems may also monitor and record access, track user behavior and detect access irregularities such as fraudulent access cards. Typical secure access systems employ a fixed control reader device and a user access card, commonly communicating through a magnetic stripe embedded on the access card or via radio frequency (RF). In RF identification (RFID) systems, an access card located within a given proximity to a card reader communicates through electromagnetic waves in the RF band. Secure cards include a secure data processing component to authenticate a valid user. Secure access systems employing RFID is generally discussed in U.S. Patent Application Publication No. 2007/0001008, the entire contents of which are hereby incorporated by reference.
Access control readers used in secure access systems are typically limited in operating environments to a nominal temperature band, commonly above 0 degree Celsius. Such an operating limitation can significantly decrease the utility of secure access systems, in particular those mounted outdoors in cold-weather climates. Any expansion of the operating envelope of such systems must be cost-efficient, simple to implement, reliable, and secure, given the highly cost-competitive nature of secure access systems and access readers/access card systems.
One example of a system intended to expand the operating temperature range of card readers is disclosed in U.S. Pat. No. 6,042,010, the entire contents of which are hereby incorporated by reference. The '010 patent employs specialized structure on a card reader to prevent foreign material from invading the circuit unit. A magnetic head holding means protrudes from the card reader main unit to the inside of the card insertion slot cover. Although seemingly effective in some situations, such as during ice build-up on a magnetic card reader system, the system is ineffective in application to more modern RFID systems.
U.S. Pat. No. 7,438,220 discloses a system to control the temperature of a secure system. The entire contents of the '220 patent are hereby incorporated by reference. The '220 publication describes an automated banking machine with a card reader involving a complex temperature control system for the reader. The '220 device is impractical for adaptation to most access control systems and is not particularly cost-effective.